Fluid-pole electric switch



' Oct. 16, 1928. 1,688,217

J. WHALEN FLUID POLE ELECTRIC SWITCH.

Filed oct. 15, 1926 JAMas Wimuan. 844mm.

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Patented a. 1c, 1928.

UNITED STATES. PATENT OFFICE.

JAMES WHALEN, OF OMAHA, NEBRASKA.

FLUID-POLE ELECTRIC swrrcn.

Application filed October 15, 1926. Serial No. 141,752.

suflicient fluidity at ordinary temperatures to assume by gravity the formation of the lowermost portion of the container in which the composition is held. A further object of my invention is to provide means for limitlng oxidation of the fluid metal composition without hermetically sealing the same to exclude air therefrom. A further object of my invention is to provide an electric switch in Wl'llCl'l the moving parts are so constructed and arranged as to be operable with a very small mechanical force, although the poles and 20.

other partsare of such conductivity as to transmit heavy electric current without heatin while the switch is closed and without ob ectionable arcing as the switch is opened. A further object of my invention is to provide a switch mechanism'having the above characteristics and adaptable to produce a multiple break of the electric circuit when in open position, whereby the switch may be em- I fployed in high-voltage circuits. so

In the accompanying drawings Fig. 1 a longitudinal section of a switch embodylng my invention, the parts being shown in circuit-opening position, Fig. 2 is a transverse section on the line 2-2 of Fig. 1, Fig. 3 is a view similar to Fig. 2 but showing the parts in circuit-closing position, Fig. 4: is a detail section on the line Jr-*4: of Fig. 1, and Fig. 5 is a detail longitudinal section through the vent-valve, the section being on the line 5-5 40 off-Fig. 2.

In carrymg out my invention according to the illustrated embodiment thereof, I provide a fixed frame comprising the metal end-mom bers or brackets and 11, secured to abase 12 of insulating material. On the lower portions of said brackets are mounted the bindingposts 13 and 14 to which are connected the terminals of the circuit to be controlled by the switch. In the upper portions of the brackets are axially alined openings in which are revolubly mounted the trunnions or p votshafts 15 and 16 of an oscillatable drum which is the movable element of the switch. Said drum comprises the' metal end-caps 17 and 18, which may be formed integrally with the pivot-shafts 15 and .16 respectively, two or more cylinder-sections 19 of insulating material such as glass, and one or more T-rings 20 disposed between the adjoining ends of the cylinder-sections 19, the flanges of the T-ring and of the end-caps fitting over the sides of the cylinder-sections as shown, and the parts being secured to each other by suitable cement 21. In the drawing the thickness of the ocment in the joints is exaggerated, and it will be understood that the actual thickness thereof is so small as to be imperceptible without such exaggeration. Each of the cylinder-sections has at the central part thereof a. transverse partition 22, formed integrally therewith, and the partition at one side of the cylinder has a substantially semi-circular opening therein, the edges of the partition at said opening being preferably rounded or beveled, and the openings of the several'sections being axially alined with each other, as shown in Fig. 1. On the pivot-shafts 15 and 16, adjoining the end-caps, are disposed the collars 23, each of which has at one side thereof a small set-screw 24 extending in to an an-v nular groove 25 in the bore thereof, and also has at the side opposite the set-screw an opening extending from said groove to the out side of the collar. Flexible conductors 26, such as are formed by fine wires braided to gether, are connectedwith the binding-posts 13 and 14:, and extended therefrom through the side-openings of the collars into the annular grooves 25, thence being extended-around in said grooves and beneath the ends-of the set-screws 24 as shown in Fig. 4, so that when the set-screws are tightened down they serve to firmly connect both the flexible conductors and the collars to the respective pivot-shafts. The end-cap 17 is provided at one side with a threaded opening in which is screwed a valvetube 27, the latter projecting into the drum and-having at its inner end a seat for the ball-valve 28 which is normally held against the seat by a spring 29, and said spring being retained in the tube by a perforate plug 30 screwed into the outer end of the tube, as shown in Fig; 5. i

Within the drum formed by the members 17, 18, 19 and 20, is disposed a body 31 of fluid metal, which is preferably of the composition hereinafter set forth, although if the switch is not to be used for heavy current the metal may be mercury only. A portion of-the space within the drum above the fluid metal is pref erably filled with a body 32 of insulating remaining space at the upper portion of the drum is left empty, or so as to be filled only with air or by vapors from the oil. When the drum is turned to a position such as shown in Fig. 3,at whichthe openings through the partitions 22 of the cylinder-sections are at the lower portion of the drum, the body 31 of fluid metal forms a conductive connection between the end-caps l7 and 18, and thus closes the circuit of which the terminals are connected with said end-caps through the collars 23, the flexible conductors 26, and the binding-posts 13 and 14. By rotation of the drum from the circuit-closing position approximately a half-revolution, the .partitions 22 are caused to cut through the body of fluid metal, thus dividing the same into a plurality of pools which are separated from each other by the partitions as shown in Fig. 1, and the circuit is thus opened at a plurality of points, the number being, according to the number of partitioned cylinder-units used in forming the drum. In order that the breaking of the circuit at the several points may be simultaneous, and arcing in high-voltage circuits thus suppressed, it is necessary that the openings through the partitions be alined with each other, and that the axis of the drum be horizontal, so that the liquid level is parallel therewith.

The fluid metal composition, which is preferably employed in the switch, is a mixture of mercury and a metal of high electrical conductivity, such as copper or silver, said metal being in small articles which are mixed with the mercury, eing immersed therein and superficially amalgamated, but not wholly dissolved therein. The resulting mass is not homogeneous, but is a slushy mixture of actual liquid with solid particles floating therein, the liquid portion of thesmixture being mercury having a small proportion 'of the other metal dissolved therein. The 'ratio of the liquid to the solid metal in the composition is such that the mass as a whole is fluid or freely mobile, and capable of flowing by gravity into the lowermost portion of u the container in which it is held, while maintaming a substantially level or horizontal uphas suflicient fluidity to operate satisfactor-- 11y 1n the described switch mechanism. A'

per surface. A suitable composition consists of one part, by weight, of copper, with three parts of mercury, the copper being finely divided into particles or granules such as are produced by filing or grinding. This composition has an electrical conductivity approximately four times that of mercury alone, and

larger proportion of the solid metal may be employed, with a corresponding increase in conductivity, by the use of the'solid metal in small uniform spherical particles. To insure the thorough amalgamation superficially of the solid metal particles, the latter may be washed with a suitable acid, capable of removing oxide from the metal, prior to-mixing with the mercury. After the metals have been mixed for a sufiicient time for the solid particles to become thoroughly coated with amalgam, the mixture is thoroughly washed to remove all traces of acid, and is then carefully dried before being used in the switch.

The switch-drum may be rotated or oscillated by any suitable actuating means consuch as the control by thermostat of electrical apparatus employing 'he'avy current, without the use of relays or intermediate switches. The actuating means is preferably so arranged that during the operationthe valvetube 27 will be constantly above the axis of the drum, so as not to of the fluid metal.

During the circuit-opening operations of the switch arcing at the fluid metalpoles is suppressed by the insulating liquid 32, and said liquid also serves at all time to limit oxidation of the fluid metal. Duringextended use of the switch some oxidation of the fluid metal will occur, because of the fact that the drum is not hermetically sealed to entirely exclude air therefrom, but as the oxide is produced in a finely divided or pulverulent form and becomes mixed with the oil and suspended therein without appreciably reducing its insulating qualities, the oxidation does not in-.

terfere with the operationof the switch except after long continued use thereof, and the switch may then be restored to its original condition by supplying fresh oil, after first fiemoying the oxide-contaminated oil from the rum.

-A Vent or safety outlet from the drum, to relieve pressure therein should the same be abnormally heated, is formed bythe valved pass below the level,

passage through the tube 27, and the valve 28 serves to exclude air from the drum, except in very minute quantities such as may be due to leakage. As before mentioned,-the insulating liquid 32 may be a. rather heavy hydro carbon oil, and when oil of this kind is used it is preferable when first preparing the switch for use to add to the heavy oil in the drum 9. drop or two of a light volatile oil such as naptha, then placing the drum so that the tube 27 is above the liquid level, and then heat- .ing the same sufiicieritly to vaporize the vola-' tile oil and thereby expel most of the air from the drum, leaving the space above the liquid filled only with the oil vapor. I have found that very satisfactory results are also attained by the use in place of mineral or hydrocarbonoil, of a non-drying fixed oil such as olive oil, which appears to prevent oxidation of the fluid metal in the switch for a longer time than the mineral oils which I have tested, possibl because the small amount of oxygen whic obtains access to the drum combines chemically with the oil itself instead of becoming merely dissolved therein and thus available for combination with the metal. I

It will be obvious that any desired number of the partitioned cylinder-sections may be employed in forming the drum, and that in operation an additional break of the circuit willbe eflected for each added partition or divider, the switch being thus adapted for use in circuits of any voltage.

Now, having described my invention, what I claim and desire to secure by Letters Patent is:

1. In an electric switch, a pole-forming composition consisting of a large number of separate small bodies of solid metal of high electrical conductivity, in combination with liquid metal connecting the bodies of solid metal interstitially and suflicient in quantity 21o rdrliake the mass as a whole substantially i 2. In an electric switch, a pole-forming composition consisting of mercury, and a large number of separate small bodies of solid metal immersed in the mercury, the mass as a whole being substantially fluid.

3. In an electric switch, a pole-forming composition consisting of mercury, and a large number of separate small bodies of solid metal immersed in and superficially amalgamated with the mercury, the mass as a whole being a slushy fluid. r

4. In an electric switch, a pole-forming composition consisting of a large number of separate small bodies of solid metal of high electrical conductivity, in combination with a quantity of liquid metal connecting the solid bodies interstitially and forming a slushy fluid mass, the liquid metal being a fluid amalgam of mercury with the metal of which the solid bodies are formed.

' JAMES WHALEN: 

